Anode and method for producing same

Abstract

The present invention relates to a negative electrode for a lithium secondary battery and a method for manufacturing the same. The negative electrode for the lithium secondary battery contains transition metal particles containing at least one of iron and nickel in a carbon-based negative electrode active material, and the concentration ratio of iron and nickel is controlled to satisfy a predetermined range. As a result, the negative electrode has the advantages of excellent life characteristics under high-temperature conditions and low electrical resistance under high-rate conditions. Furthermore, a lithium secondary battery containing the negative electrode can be characterized by excellent high-temperature life characteristics and high-rate charge / discharge performance.

Description

[Technical Field]

[0001] The present invention relates to a negative electrode and a method for producing the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0158093, filed November 15, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] Lithium secondary batteries are widely used not only in small devices such as portable electronic devices, but also in medium- to large-sized devices such as battery packs for hybrid and electric vehicles, power storage devices, etc. In particular, with the growing interest in environmental issues in recent years, much research has been conducted on electric vehicles and hybrid electric vehicles that can replace vehicles that use fossil fuels such as gasoline and diesel vehicles, which are one of the main causes of air pollution, and research on high-capacity secondary batteries that can power these electric vehicles and hybrid electric vehicles has also been actively conducted.

[0004] Secondary batteries are rechargeable batteries and include conventional Ni / Cd batteries, Ni / MH batteries, and more recent lithium-ion batteries. Among these secondary batteries, lithium-ion batteries have almost no memory effect compared to Ni / Cd batteries, Ni / MH batteries, and can be freely charged and discharged, have a low self-discharge rate, and have a high energy density. Furthermore, lithium-ion batteries can be manufactured to be compact and lightweight, making them highly useful as a power source for mobile devices. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2017-0011566 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an anode having excellent life characteristics under high temperature conditions and excellent electrical performance under high speed conditions, and a method for producing the same. [Means for solving the problem]

[0007] To solve the above problem, One embodiment of the present invention comprises: a negative electrode current collector; and a negative electrode active layer provided on at least one surface of the negative electrode current collector and including a carbon-based negative electrode active material, The carbon-based negative electrode active material contains magnetic transition metal particles, the transition metal particles include iron and nickel; The carbon-based negative electrode active material contains magnetic transition metal particles at a concentration of 1,200 ppm or less, The carbon-based negative electrode active material has a concentration ratio of iron to nickel (Fe / Ni) of 2.5 to 13.0.

[0008] The iron concentration can range from 0.1 ppm to 1,000 ppm.

[0009] The nickel concentration can range from 0.01 ppm to 500 ppm.

[0010] The carbon-based negative electrode active material may contain transition metal particles at a concentration in the range of 0.01 ppm to 1,100 ppm.

[0011] Furthermore, the magnetic transition metal particles may contain iron in an amount of 50% or more based on the total weight.

[0012] The magnetic transition metal particles may further contain one or more of cobalt, chromium, zinc, magnesium, manganese, and copper.

[0013] Furthermore, the carbon-based negative electrode active material may be artificial graphite in the form of secondary particles formed by granulating primary particles.

[0014] Moreover, one embodiment of the present invention is a step of applying a negative electrode slurry containing a carbon-based negative electrode active material to at least one surface of a negative electrode current collector and drying the slurry to form a negative electrode active layer; The carbon-based negative electrode active material contains magnetic transition metal particles, the transition metal particles include iron and nickel; The carbon-based negative electrode active material contains magnetic transition metal particles at a concentration of 1,200 ppm or less, The carbon-based negative electrode active material has a concentration ratio of iron to nickel (Fe / Ni) of 2.5 to 13.0.

[0015] Here, the carbon-based negative electrode active material may be prepared by a method including a step (S1) of graphitizing a carbon raw material and a step (S2) of carbonizing the graphitized carbon raw material, and a step (S3) of adjusting the concentration of magnetic transition metal particles present in the carbon raw material by applying a magnetic field at least once before and after the carbonization step.

[0016] The step (S3) of adjusting the concentration of the transition metal particles may involve applying a magnetic field with an intensity of 1,000 G to 40,000 G for 1 second to 600 seconds.

[0017] In addition, the step (S3) of adjusting the concentration of the transition metal particles may be performed before or after the step of carbonizing the graphitized carbon raw material.

[0018] The iron concentration may be in the range of 0.1 ppm to 1,000 ppm.

[0019] The nickel concentration can range from 0.01 ppm to 500 ppm.

[0020] Furthermore, the magnetic transition metal particles may further contain one or more of cobalt, chromium, zinc, magnesium, manganese, and copper. [Effects of the Invention]

[0021] The negative electrode according to the present invention has the advantages of excellent life characteristics under high temperature conditions and low electrical resistance under high-rate conditions, and therefore, a lithium secondary battery including the negative electrode can have excellent high-temperature life characteristics and high-rate charge / discharge performance. DETAILED DESCRIPTION OF THE INVENTION

[0022] Because the present invention is susceptible to various modifications and variations, specific embodiments will be described in detail.

[0023] However, this is not intended to limit the invention to any particular embodiment, but rather it can be understood to include all modifications, equivalents, or alternatives falling within the scope of the present invention.

[0024] In the present invention, the terms "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and can be understood as not precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0025] Additionally, in the present invention, "comprising as a main component" may mean containing 50 wt% or more (or 50 vol% or more), 60 wt% or more (or 60 vol% or more), 70 wt% or more (or 70 vol% or more), 80 wt% or more (or 80 vol% or more), 90 wt% or more (or 90 vol% or more), or 95 wt% or more (or 95 vol% or more) of a component defined relative to the total weight (or total volume). For example, "comprising graphite as a main component as a negative electrode active material" may mean containing 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, or 95 wt% or more of graphite relative to the total weight of the negative electrode active material. In some cases, it may mean that the entire negative electrode active material is composed of graphite, with the graphite content being 100 wt%.

[0026] In addition, in this specification, "average particle size (D 50 The above average particle size (D ) is the particle size at the point where the volume percentage reaches 50% from the cumulative curve of particle size distribution when the total volume is taken as 100%, and is the particle size at which the volume percentage reaches 50% from the cumulative curve, accumulating from the smallest particle size. 50 ) can be measured using, for example, the laser diffraction method, which is generally capable of measuring particle sizes from the submicron range to several mm, and can provide results with high reproducibility and high resolution.

[0027] In addition, in this specification, "magnetism" refers to the property of a material to be magnetized. The magnetism can be classified into semi-magnetism, paramagnetism, ferromagnetism, etc. depending on the direction of magnetization depending on the direction of the applied external magnetic field or whether or not an external magnetic field is applied during magnetization.

[0028] As used herein, "about," "approximately," and "substantially" mean within or near the range of a given numerical value or degree, taking into account inherent manufacturing and material tolerances.

[0029] A lithium secondary battery is a power generating element that can be charged and discharged and consists of a laminated structure of a positive electrode, a separator, and a negative electrode. When a lithium secondary battery is charged, a lithium desorption reaction occurs in which lithium contained in the positive electrode active material is oxidized and released at the positive electrode inside the battery, and a lithium insertion reaction occurs in which lithium is reduced at the negative electrode and inserted into the negative electrode active material.

[0030] In reality, the negative electrode widely uses a material containing graphite carbon as the negative electrode active material. When a material containing graphite carbon releases lithium, the average potential is about 0.2 V (Li / Li + Therefore, when graphite-based carbon is used as the negative electrode active material, the secondary battery has the advantage of having a high and constant voltage.

[0031] Amorphous carbon or crystalline carbon is used as the negative electrode active material, and crystalline carbon is the most widely used due to its high capacity. Such crystalline carbon includes graphite-based carbon such as natural graphite and artificial graphite.

[0032] Meanwhile, the characteristics of graphite-based carbons vary depending on the type. For example, natural graphite is inexpensive and exhibits excellent adhesion to current collectors, but is relatively inferior to artificial graphite in terms of high-speed charge / discharge performance and lifespan. However, because artificial graphite has few surface defects and functional groups, when propylene carbonate (PC), for example, is mixed into the electrolyte to improve low-temperature performance, the propylene carbonate can exfoliate and destroy the layers that make up the interlayer structure of the graphite. Such graphite exfoliation reduces the lifespan of the negative electrode under high-temperature conditions and increases resistance under high-speed conditions, limiting the degradation of fast charging performance.

[0033] In consideration of these points, the present invention provides a negative electrode technology for a secondary battery that can provide excellent life characteristics under high temperature conditions and improved electrical performance under high speed conditions.

[0034] The present invention will now be described in more detail.

[0035] <Negative electrode> One embodiment of the present invention comprises: a negative electrode current collector; and a negative electrode active layer provided on at least one surface of the negative electrode current collector and including a carbon-based negative electrode active material, The carbon-based negative electrode active material contains magnetic transition metal particles, the magnetic transition metal particles contain iron and nickel; The carbon-based negative electrode active material has a concentration ratio of iron to nickel (Fe / Ni) of 2.5 to 13.0.

[0036] The negative electrode according to the present invention may be used in a lithium secondary battery. The negative electrode includes a negative electrode active layer on at least one surface of a negative electrode current collector. The negative electrode active layer is a layer that realizes electrical activity of the negative electrode and includes, as a main component, a negative electrode active material that realizes an electrochemical oxidation-reduction reaction during charge and discharge of the battery.

[0037] Here, the negative electrode active material may contain a carbon-based negative electrode active material as a main component.

[0038] Specifically, the carbon-based negative electrode active material may be included in an amount of 80 to 99.8 parts by weight relative to the total weight of the negative electrode active layer. For example, the carbon-based negative electrode active material may be included in an amount of 95 parts by weight or more, 98 parts by weight or more, 84 to 99.8 parts by weight, 90 to 99.8 parts by weight, 94 to 99.8 parts by weight, 88 to 96 parts by weight, or 92 to 97.5 parts by weight relative to the total weight of the negative electrode active layer.

[0039] The carbon-based negative electrode active material refers to a material primarily composed of carbon atoms, and may include graphite. The graphite may include at least one of natural graphite and artificial graphite. For example, the carbon-based negative electrode active material may include natural graphite or artificial graphite alone, or may include a mixture of natural graphite and artificial graphite in some cases.

[0040] For example, the carbon-based negative electrode active material may contain natural graphite and artificial graphite in a weight ratio of 5-50:50-95, 20-45:55-80, or 30-50:50-70. In this case, by containing natural graphite and artificial graphite in the above-mentioned mixing ratio, the carbon-based negative electrode active material can strengthen the adhesion between the negative electrode current collector and the negative electrode active layer.

[0041] In addition, the carbon-based negative electrode active material may contain artificial graphite alone. The present invention significantly extends the life of the negative electrode by containing artificial graphite alone in the negative electrode active layer, making it advantageous for use in applications requiring frequent charging over long periods of time, such as automobile batteries. Furthermore, compared to natural graphite, artificial graphite is advantageous for fast charging and has the advantage of superior output performance.

[0042] The carbon-based negative electrode active material is preferably spherical graphite secondary particles formed by the aggregation of multiple flake-shaped graphite primary particles. Examples of flake graphite include natural graphite, artificial graphite, mesophase calcined carbon (bulk mesophase) made from tar or pitch, and graphitized cokes (raw coke, green coke, pitch coke, needle coke, petroleum coke, etc.). Granulated graphite made from multiple highly crystalline artificial graphite particles is particularly preferred. Each graphite granule may be formed by the aggregation of 2 to 100, preferably 3 to 20, flake graphite particles.

[0043] The average particle size of the secondary particles (D 50 ) can be in the range of 1 μm to 50 μm. For example, 50) can be in the range of 1 μm to 40 μm, 1 μm to 30 μm, 10 μm to 40 μm, 15 μm to 30 μm, 25 μm to 50 μm, 11 μm to 19 μm, 15 μm to 25 μm, 20 μm to 30 μm, 1 μm to 20 μm, 1 μm to 10 μm, 5 μm to 15 μm, 10 μm to 20 μm, 15 μm to 30 μm, 15 μm to 20 μm, 21 μm to 26 μm, 25 μm to 30 μm, 11 μm to 17 μm, 16 μm to 23 μm, 2 μm to 7 μm, 0.5 μm to 5 μm, or 1 μm to 3 μm. For spherical carbon-based negative electrode active materials, it is advantageous to minimize particle size to maximize the degree of disorder in the direction of expansion of each particle, thereby preventing particle expansion during lithium ion charging. However, when the particle size of the carbon-based negative electrode active material is less than 1.0 μm, the number of particles per unit volume increases, requiring a large amount of binder, which can result in low sphericity and sphericity yield. On the other hand, when the maximum particle size exceeds 50 μm, the expansion rate of the negative electrode active material during charge / discharge of the secondary battery increases significantly. This can lead to a decrease in the adhesion between particles of the negative electrode active material and between the negative electrode active material particles and the current collector as the charge / discharge cycles are repeated, resulting in a significant decrease in cycle performance.

[0044] The carbon-based negative electrode active material may have a form in which magnetic transition metal particles are uniformly dispersed. The transition metal particles refer to particles containing a transition metal, and the transition metal may be included in the form of a transition metal, a transition metal oxide, a transition metal nitride, a transition metal phosphate, or a transition metal alloy.

[0045] The magnetic transition metal particles include magnetizable transition metals, specifically iron (Fe) and nickel (Ni). Such transition metal particles may be inevitably included during the manufacturing process of a carbon-based negative electrode active material. The present invention includes magnetic transition metal particles in a carbon-based negative electrode active material, thereby further improving the charge / discharge performance of the carbon-based negative electrode active material under high-rate and / or high-temperature conditions. The transition metal particles may include iron and nickel within predetermined concentration ranges, and these may have a predetermined concentration ratio. The concentrations of the transition metal particles and / or transition metals may be measured using an inductively coupled plasma emission spectrometer (ICP-OES), for example.

[0046] For example, the iron may be contained in the carbon-based negative electrode active material at a concentration ranging from 0.1 ppm to 1,000 ppm. For example, the iron may be contained in the carbon-based negative electrode active material at a concentration ranging from 0.1 ppm to 900 ppm, 0.1 ppm to 800 ppm, 0.1 ppm to 750 ppm, 0.1 ppm to 500 ppm, 0.1 ppm to 250 ppm, 0.1 ppm to 100 ppm, 0.1 ppm to 50 ppm, 0.1 ppm to 10 ppm, 0.1 ppm to 5 ppm, 0.1 ppm to 1 ppm, 0.5 ppm to 4 ppm, 10 ppm to 990 ppm, 100 ppm to 990 ppm, 200 ppm to 990 ppm, 500 ppm to 990 ppm, 750 ppm to 990 ppm, 1.0 ppm to 4.9 ppm, 0.3 ppm to 1.8 ppm, or 0.1 ppm to 0.9 ppm.

[0047] The nickel may be contained in the carbon-based negative electrode active material at a concentration ranging from 0.01 ppm to 500 ppm. For example, the nickel may be contained at a concentration in the range of 0.01 ppm to 300 ppm, 0.01 ppm to 200 ppm, 0.01 ppm to 150 ppm, 0.01 ppm to 115 ppm, 0.01 ppm to 100 ppm, 0.01 ppm to 75 ppm, 0.01 ppm to 50 ppm, 0.01 ppm to 25 ppm, 0.01 ppm to 10 ppm, 0.01 ppm to 5 ppm, 0.01 ppm to 3 ppm, 0.01 ppm to 1.5 ppm, 1 ppm to 3 ppm, 10 ppm to 200 ppm, 50 ppm to 200 ppm, 80 ppm to 150 ppm, 110 ppm to 190 ppm, 0.10 ppm to 0.95 ppm, or 0.2 ppm to 1.1 ppm.

[0048] The carbon-based negative electrode active material may contain, in addition to iron and nickel, a transition metal other than iron and nickel, and may contain a total magnetic transition metal particle concentration of 1,200 ppm or less. For example, the carbon-based negative electrode active material may contain 0.01 ppm to 1,200 ppm, 0.01 ppm to 1,100 ppm, 0.05 ppm to 1,050 ppm, 0.1 ppm to 990 ppm, 0.1 ppm to 500 ppm, 0.1 ppm to 100 ppm, 0.1 ppm to 50 ppm, 0.1 ppm to 10 ppm, 0.1 ppm to 5 ppm, 0.1 ppm to 1 ppm, 0.5 ppm to 4 ppm, 110 ppm to 1,000 ppm, or 110 ppm to 1,000 ppm. The magnetic transition metal particles may be contained therein at a concentration in the range of 0 ppm, 110 ppm to 800 ppm, 110 ppm to 600 ppm, 110 ppm to 400 ppm, 200 ppm to 650 ppm, 200 ppm to 990 ppm, 500 ppm to 990 ppm, 800 ppm to 990 ppm, 1.0 ppm to 4.9 ppm, 0.8 ppm to 2.3 ppm, or 0.1 ppm to 0.9 ppm.

[0049] The transition metal may be a magnetic transition metal or, in some cases, a non-magnetic transition metal. The transition metal may include both a magnetic and a non-magnetic transition metal. For example, the non-magnetic transition metal may exist in the form of an alloy with the magnetic transition metal, thereby being detected together with the magnetic transition metal. The present invention adjusts the concentrations of iron, nickel, and all transition metal particles having magnetic properties other than iron and nickel contained in the carbon-based negative electrode active material within the above ranges to suppress or prevent a decrease in charge mobility from the positive electrode during charging and discharging of the secondary battery, which would be caused by an excessive concentration exceeding the above-mentioned upper limit. In particular, if the concentration of transition metal particles in the carbon-based negative electrode active material exceeds the above-mentioned upper limit, the electrical resistance of the carbon-based negative electrode active material may decrease slightly, but this may induce side reactions with the electrolyte during charging and discharging of the secondary battery, thereby reducing the initial efficiency. In this case, gas is generated due to decomposition of the electrolyte during charging and discharging of the secondary battery, which limits the safety of the secondary battery. In addition, the present invention can prevent a decrease in the capacity of the negative electrode during high-speed charge / discharge due to a concentration lower than the above-mentioned lower limit, or prevent fires or explosions due to various mechanisms of the secondary battery.

[0050] The concentration ratio of iron to nickel (Fe / Ni) contained in the carbon-based negative electrode active material may be in the range of 2.5 to 13.0. For example, the concentration ratio of iron to nickel (Fe / Ni) contained in the carbon-based negative electrode active material may be in the range of 2.5 to 12.0, 2.5 to 10.0, 2.5 to 8.0, 2.5 to 5.5, 2.5 to 4.5, 2.5 to 4.1, 2.5 to 3.9, 3.25 to 9.5, 3.2 to 8.5, 3.2 to 6.5, 3.2 to 4.5, 3.2 to 3.9, 3.5 to 8.5, 4.0 to 5.5, 5.0 to 8.5, 6.0 to 13.0, 9.0 to 13.0, 2.8 to 12.5, or 3.2 to 7.9.

[0051] By adjusting the concentration ratio of iron and nickel contained in the carbon-based negative electrode active material to fall within the above range, the present invention can suppress or prevent an increase in the electrical resistance of the negative electrode during high-rate charge / discharge and a decrease in lifespan during high-temperature charge / discharge, which would be caused by a ratio higher than the above upper limit or a ratio lower than the above lower limit.

[0052] The magnetic transition metal particles may contain transition metal elements other than iron and nickel. For example, the transition metal particles may further contain one or more of cobalt, chromium, zinc, magnesium, manganese, and copper. The transition metal may be contained within the particles in the form of a transition metal, transition metal oxide, transition metal nitride, transition metal phosphate, or transition metal alloy.

[0053] In this case, the magnetic transition metal particles may contain 50% or more iron by weight, for example, 50% to 95%, 50% to 90%, 55% to 90%, 60% to 90%, 65% to 90%, 75% to 90%, 80% to 90%, 55% to 85%, 55% to 80%, 60% to 80%, 60% to 70%, 70% to 85%, 58% to 69%, 62% to 81%, or 76% to 89% iron.

[0054] The present invention has the advantage that, by ensuring that the proportion of iron contained in the transition metal particles satisfies the above range, the electrical conductivity of the negative electrode can be increased without causing a side reaction with the electrolyte impregnated in the negative electrode active layer during charging and discharging of the secondary battery.

[0055] Meanwhile, the negative electrode active layer according to the present invention may further include, in addition to the carbon-based negative electrode active material as the main component, a conductive material, a binder, and other additives, as needed.

[0056] The conductive material may include one or more of carbon black, acetylene black, ketjen black, carbon nanotubes, carbon fibers, etc., but is not limited thereto.

[0057] For example, the negative electrode active layer may contain carbon black, carbon nanotubes, carbon fibers, etc., alone or in combination as a conductive material.

[0058] The content of the conductive material may be 0.1 to 10 parts by weight, based on 100 parts by weight of the total negative electrode active layer. For example, the content of the conductive material may be 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, 2 to 6 parts by weight, or 0.5 to 2 parts by weight, based on 100 parts by weight of the total negative electrode active layer. By controlling the content of the conductive material within the above range, the present invention can prevent a decrease in charge capacity due to an increase in negative electrode resistance caused by a low content of conductive material, and can prevent problems such as a decrease in charge capacity due to a decrease in the content of negative electrode active material caused by an excessive amount of conductive material, or a decrease in fast charge characteristics due to an increase in the loading amount of the negative electrode active layer.

[0059] The binder is a component that aids in bonding the negative electrode active material and conductive material and the current collector, and can be appropriately used within a range that does not degrade the electrical properties of the electrode. Examples of such binders include one or more of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber (SBR), and fluororubber.

[0060] The content of the binder may be 0.1 to 10 parts by weight, based on 100 parts by weight of the total negative electrode active layer. For example, the content of the binder may be 0.1 to 8 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, or 2 to 6 parts by weight, based on 100 parts by weight of the total negative electrode active layer. By controlling the content of the binder contained in the negative electrode active layer within the above range, the present invention can prevent a decrease in the adhesive strength of the active layer due to a low content of binder or a decrease in the electrical properties of the electrode due to an excessive amount of binder.

[0061] The average thickness of the negative electrode active layer may be in the range of 50 μm to 500 μm. For example, the average thickness of the negative electrode active layer may be in the range of 100 μm to 400 μm, 200 μm to 350 μm, 50 μm to 180 μm, 80 μm to 150 μm, 100 μm to 250 μm, 100 μm to 250 μm, or 130 μm to 190 μm. The average thickness of the negative electrode active layer may be measured by scanning electron microscope (SEM) analysis of a cross section of the negative electrode in the thickness direction. By adjusting the average thickness of the negative electrode active layer within the above range, the present invention can realize not only high adhesion between the negative electrode active layer and the negative electrode current collector but also high energy density of the negative electrode.

[0062] Furthermore, the negative electrode current collector is not particularly limited as long as it has high conductivity and does not induce chemical changes in the battery. For example, the negative electrode current collector can be made of copper, stainless steel, nickel, titanium, calcined carbon, etc., and in the case of copper or stainless steel, it can also be surface-treated with carbon, nickel, titanium, silver, etc. In addition, the average thickness of the negative electrode current collector can be appropriately selected from 1 μm to 500 μm, taking into account the conductivity and total thickness of the negative electrode to be manufactured.

[0063] The negative electrode according to the present invention has the above-described structure, which has the advantages of excellent life characteristics under high temperature conditions and low electrical resistance under high-rate conditions, and therefore a lithium secondary battery including the negative electrode can have excellent high-temperature life characteristics and high-rate charge / discharge performance.

[0064] <Method of manufacturing the negative electrode> Furthermore, one embodiment of the present invention is a step of applying a negative electrode slurry containing a carbon-based negative electrode active material to at least one surface of a negative electrode current collector and drying the slurry to form a negative electrode active layer; The carbon-based negative electrode active material contains magnetic transition metal particles, the transition metal particles include iron and nickel; The method for producing a negative electrode is characterized in that the concentration ratio (Fe / Ni) of iron to nickel contained in the carbon-based negative electrode active material is 2.5 to 13.0.

[0065] The method for manufacturing the anode according to the present invention refers to a method for manufacturing the anode according to the present invention described above. The method for manufacturing the anode may include coating an anode slurry on an anode current collector and drying the coated anode slurry to form an anode active layer, thereby manufacturing an anode for a lithium secondary battery.

[0066] The negative electrode slurry may include a carbon-based negative electrode active material as a main component, and the carbon-based negative electrode active material may have a form in which magnetic transition metal particles are uniformly dispersed. The transition metal particles refer to particles containing a transition metal, and the transition metal may be included in the form of a transition metal, transition metal oxide, transition metal nitride, or transition metal phosphate. The transition metal particles include a magnetizable transition metal, specifically, iron (Fe) and nickel (Ni).

[0067] The carbon-based negative electrode active material may be prepared by a method including a step (S1) of graphitizing a carbon raw material and a step (S2) of carbonizing the graphitized carbon raw material, and a step (S3) of applying a magnetic field to the graphitized carbon raw material at least once before and after the carbonization step to adjust the concentration of magnetic transition metal particles present in the carbon raw material.

[0068] The graphitization step (S1) refers to a process of converting the disordered structure of the carbon raw material into an ordered graphite structure by heat treating the carbon raw material at a temperature of 2,500° C. or more.

[0069] Here, the "carbon raw material" may include one or more of needle cokes, mosaic cokes, coal tar pitch, and resin pitch.

[0070] The graphitizing step (S1) can be carried out using an apparatus such as an Acheson graphitization furnace, a box-type graphitization furnace, or a lengthwise graphitization furnace.

[0071] The graphitization step (S1) can be performed at any heat treatment temperature that can induce a physical change from the structure of the disordered carbon raw material to an ordered structure like graphite, without any particular limitations. For example, the graphitization step (S1) can be performed at a temperature in the range of 2,000°C to 3,500°C, 2,500°C to 3,500°C, 2,800°C to 3,500°C, or 2,800°C to 3,200°C.

[0072] In the present invention, by performing the graphitization step (S1) within the above temperature range, it is possible to easily induce a change in the physical structure of the carbon raw material. The resulting product has high crystallinity, which results in excellent electrical properties when used in a negative electrode. In addition, since sublimation on the surface of the carbon raw material during heat treatment is suppressed, there is an advantage in that the process efficiency is excellent.

[0073] The carbon raw material obtained in the graphitizing step (S1) may be obtained by removing a portion of the carbon raw material present at the top of the graphitized carbon raw material. During graphitization of the carbon raw material, foreign matter such as transition metals and nonmetals present inside the carbon raw material may volatilize. However, in the case of some transition metals, the boiling point of which is equal to or slightly higher than the graphitization temperature and therefore may not be completely volatilized, and a portion of the carbon raw material may remain at the top of the graphitized carbon raw material. Therefore, this step (S1) may be obtained by removing a predetermined carbon raw material present at the top when the graphitized carbon raw material is removed from the reactor. The removed carbon raw material may be a carbon raw material present at a depth of 10% or less, 5% or less, or 3% or less of the total depth of the carbon raw material from the surface of the carbon raw material among the carbon raw material introduced into the reactor and graphitized.

[0074] Next, the step (S2) of carbonizing the graphitized carbon raw material refers to a process of granulating and densifying the graphitized carbon raw material. To this end, in the present invention, the graphitized carbon raw material may be carbonized in a state where it is mixed with pitch.

[0075] The carbon raw material graphitized in the graphitization step (S1) may have the form of spherical secondary particles formed by granulating scaly primary particles. When the graphitized carbon raw material is uniformly mixed with pitch and then carbonized, the mixed pitch fixes the carbon raw material adsorbed on the surface of the carbon raw material, thereby obtaining more stable spherical secondary particles. Furthermore, the spherical secondary particles have increased density due to the surface pitch, thereby enabling the negative electrode active layer to achieve high energy density.

[0076] The "pitch" is a material mainly made from coal or by-products of petrochemical processes, and can be either a commonly used solid or liquid pitch. The solid pitch can be obtained by grinding coal tar pitch, petroleum pitch, synthetic pitch, wood tar pitch, etc. The liquid pitch can be produced by dissolving a liquid resin or a solid pitch in a solvent, coating it, and then carbonizing it. Examples of solvents that can be used include hexane, toluene, tetrahydrofuran (THF), quinoline, N-methylpyrrolidone (NMP), and ethanol.

[0077] The solid phase pitch has an average particle size (D 50 The average particle size (D) of the solid phase pitch may be in the range of 1 μm to 7 μm, or 2 μm to 4 μm. 50 When the ratio (R) satisfies this range, the additives are uniformly distributed and mixed among the negative electrode active material particles, thereby allowing the surfaces of the negative electrode active material particles to be more uniformly coated.

[0078] The pitch may be used in an amount of 1 to 10 parts by weight, or 3 to 5 parts by weight, based on 100 parts by weight of the graphitized carbon raw material. By adjusting the amount of pitch mixed during carbonization of the graphitized carbon raw material within the above range, the present invention can prevent a significant increase in the content of transition metal particles contained in the carbon-based negative electrode active material, which would be produced if the pitch content were higher than the above-mentioned upper limit. Furthermore, the present invention can prevent a decrease in structural stability due to lithium intercalation / deintercalation of the carbon-based negative electrode active material during charge / discharge of the secondary battery, which would be produced if the pitch content were lower than the above-mentioned lower limit.

[0079] In addition, in step (S2), the graphitized carbon raw material and the pitch may be homogenized using a homogenizer to uniformly mix them. The homogenizer may be any homogenizer commonly used in the art without any particular limitations. For example, the homogenizer may be a vertical / horizontal mixer, an ultrasonic homogenizer, etc.

[0080] The carbonization step (S2) may be performed at a predetermined temperature range, for example, 1,000°C to 2,600°C, 1,500°C to 2,000°C, or 1,500°C to 1,600°C.

[0081] The magnetic transition metal particles may be mixed into the carbon raw material by abrasion in a grinding device during the grinding process of the carbon raw material before graphitization, or in some cases by abrasion in a homogenizing device during carbonization of the graphitized carbon raw material. Although it is more difficult to control the concentration of the introduced transition metal particles compared to when transition metal particles are intentionally mixed into the carbon raw material during the preparation of a carbon-based negative electrode active material, the introduced transition metal particles may exhibit better electrical properties at high temperatures.

[0082] Therefore, the method for manufacturing a negative electrode according to the present invention includes a step (S3) of adjusting the concentration of magnetic transition metal particles in the carbon-based negative electrode active material by applying a magnetic field to remove the transition metal particles before and / or after the step (S2) of carbonizing the graphitized carbon raw material, in order to adjust the concentration of magnetic transition metal particles in the carbon-based negative electrode active material.

[0083] For example, the transition metal particles can be removed by applying a magnetic field to the graphitized carbon feedstock prior to carbonization (S2) of the carbon feedstock.

[0084] The transition metal particles can also be removed by applying a magnetic field to the graphitized carbon material after carbonization (S2).

[0085] Because the transition metal particles are magnetic, they can be easily removed by applying a magnetic field to the carbon raw material in step (S3). This allows for the concentration of transition metal particles contained in the resulting carbon-based negative electrode active material to be adjusted. However, if a magnetic field is applied twice to the graphitized carbon raw material, the concentration of transition metal particles remaining in the carbon raw material may be significantly reduced. In this case, the concentration ratio of iron and nickel present in the carbon-based negative electrode active material may be significantly reduced, resulting in a decrease in high-temperature charge / discharge performance or an increase in the electrical resistance of the negative electrode under high-rate conditions.

[0086] Here, the step (S3) of adjusting the concentration of the transition metal particles may be performed for a certain period of time at a magnetic field intensity that satisfies a predetermined range using an electromagnet or a permanent magnet.

[0087] For example, this step (S3) can be performed by applying a magnetic field with a strength in the range of 1,000 G to 40,000 G (Gauss), specifically, by applying a magnetic field with a strength in the range of 5,000 G to 40,000 G, 20,000 G to 40,000 G, or 36,000 G to 40,000 G.

[0088] Furthermore, this step (S3) can be performed for 1 to 600 seconds, specifically 10 to 600 seconds, 30 to 600 seconds, 60 to 600, 100 to 500 seconds, 200 to 400 seconds, or 250 to 350 seconds.

[0089] In the present invention, the concentration of transition metal particles in the carbon-based negative electrode active material can be more easily controlled by adjusting the magnetic field strength and application time in the step (S3) of controlling the concentration of transition metal particles within the above ranges.

[0090] The carbon-based negative electrode active material thus prepared contains transition metal particles, and the transition metal particles may contain iron and nickel in respective predetermined concentration ranges, and the concentrations of the transition metal particles and / or the transition metal may be measured using an inductively coupled plasma emission spectrometer (ICP-OES).

[0091] For example, the iron may be contained in the carbon-based negative electrode active material at a concentration ranging from 0.1 ppm to 1,000 ppm. For example, the iron may be contained in the carbon-based negative electrode active material at a concentration ranging from 0.1 ppm to 900 ppm, 0.1 ppm to 800 ppm, 0.1 ppm to 750 ppm, 0.1 ppm to 500 ppm, 0.1 ppm to 250 ppm, 0.1 ppm to 100 ppm, 0.1 ppm to 50 ppm, 0.1 ppm to 10 ppm, 0.1 ppm to 5 ppm, 0.1 ppm to 1 ppm, 0.5 ppm to 4 ppm, 10 ppm to 990 ppm, 100 ppm to 990 ppm, 200 ppm to 990 ppm, 500 ppm to 990 ppm, 750 ppm to 990 ppm, 1.0 ppm to 4.9 ppm, 0.3 ppm to 1.8 ppm, or 0.1 ppm to 0.9 ppm.

[0092] The nickel may be contained in the carbon-based negative electrode active material at a concentration of 0.01 ppm to 500 ppm. For example, the nickel may be contained in the carbon-based negative electrode active material at a concentration of 0.01 ppm to 300 ppm, 0.01 ppm to 200 ppm, 0.01 ppm to 150 ppm, 0.01 ppm to 115 ppm, 0.01 ppm to 100 ppm, 0.01 ppm to 75 ppm, 0.01 ppm to 50 ppm, 0.01 ppm to 25 ppm, 0.01 ppm to 10 ppm, 0.01 ppm to 100 ppm, 0.01 ppm to 115 ppm, 0.01 ppm to 10 ... It may be included at concentrations ranging from 0.01 ppm to 5 ppm, 0.01 ppm to 3 ppm, 0.01 ppm to 1.5 ppm, 1 ppm to 3 ppm, 10 ppm to 200 ppm, 50 ppm to 200 ppm, 80 ppm to 150 ppm, 110 ppm to 190 ppm, 0.10 ppm to 0.95 ppm, or 0.2 ppm to 1.1 ppm.

[0093] In addition, the magnetic transition metal particles may contain transition metal elements other than iron and nickel. For example, the transition metal particles may further contain one or more of cobalt, chromium, zinc, magnesium, manganese, and copper. The transition metal may be contained within the particles in the form of a transition metal, transition metal oxide, transition metal nitride, or transition metal phosphate.

[0094] Meanwhile, the negative electrode slurry can be applied by discharging and coating the negative electrode slurry containing a carbon-based negative electrode active material onto the surface of a moving negative electrode current collector. This process can be performed using any method commonly used in the art, but is preferably a die coating method. The die coating method can be performed using a slot die equipped with a shim for controlling the discharging conditions of the negative electrode slurry. In this case, the loading amount and coating thickness of the negative electrode slurry applied to the negative electrode current collector can be easily controlled by controlling the shape and position of the shim.

[0095] The negative electrode slurry contains a carbon-based negative electrode active material as a main component, and may optionally further contain a conductive material, a binder, other additives, etc. The composition of the negative electrode slurry is the same as that of the negative electrode active layer formed therefrom, and therefore, detailed description thereof will be omitted.

[0096] The negative electrode slurry may be dried by any method commonly used in the art for drying electrode active layers, without any particular limitations. For example, the drying may be performed by applying thermal energy to the negative electrode slurry using a hot air dryer, a vacuum oven, or the like.

[0097] The method according to the present invention may further include rolling the negative electrode active layer formed by drying the negative electrode slurry. The rolling is a step of applying pressure to the surface of the negative electrode active layer formed using a roll press or the like to increase the energy density of the negative electrode active layer. The rolling may be performed at a temperature higher than room temperature.

[0098] For example, the rolling can be carried out at a temperature in the range of 50°C to 100°C, more specifically at a temperature in the range of 60°C to 100°C, 75°C to 100°C, 85°C to 100°C, 50°C to 90°C, 60°C to 80°C, or 65°C to 90°C.

[0099] The rolling can be performed at a rolling speed in the range of 2 m / s to 7 m / s, more specifically, at a rolling speed in the range of 2 m / s to 6.5 m / s, 2 m / s to 6 m / s, 2 m / s to 5.5 m / s, 2 m / s to 5 m / s, 2 m / s to 4.5 m / s, 2 m / s to 4 m / s, 2.5 m / s to 4 m / s, 2.5 m / s to 3.5 m / s, 3.5 m / s to 5 m / s, 5 m / s to 7 m / s, 5.5 m / s to 6.5 m / s, or 6 m / s to 7 m / s.

[0100] The rolling can be carried out under a pressure condition in the range of 50 MPa to 200 MPa, specifically, under a pressure condition in the range of 50 MPa to 150 MPa, 50 MPa to 100 MPa, 100 MPa to 200 MPa, 150 MPa to 200 MPa, or 80 MPa to 140 MPa.

[0101] According to the present invention, by carrying out the rolling under the above-mentioned temperature, speed and / or pressure conditions, the energy density of the negative electrode can be easily increased without damaging the negative electrode active layer.

[0102] The method for producing a negative electrode according to the present invention has the above-described configuration, and thus can contain transition metal particles containing iron and nickel at a predetermined concentration and concentration ratio in the carbon-based negative electrode active material, which provides the negative electrode with the advantages of excellent life characteristics under high-temperature conditions and low electrical resistance under high-speed conditions.

[0103] The present invention will be described in more detail below with reference to examples and experimental examples.

[0104] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0105] <Examples 1 to 8 and Comparative Examples 1 to 5. Production of Negative Electrodes> 1) Manufacturing of carbon-based negative electrode active materials Coke raw material was prepared as a carbon raw material. The prepared coke raw material had an average particle size (D 50 The coke raw material was pulverized using a jet mill until the particle size reached 10 μm. The pulverized coke raw material was granulated using a horizontal granulator at 800°C for 24 hours.

[0106] The granulated coke raw material was graphitized by heat treatment at 2800°C for 400 hours using an Acheson graphitization furnace. When the graphitized product was removed from the graphitization furnace, the top product was removed from the surface of the product to a depth of 3% of the total depth of the product. The presence or absence of the top product is shown in Table 1 below.

[0107] 100 parts by weight of the graphitized product and 5 parts by weight of solid-phase pitch were mixed in a vertical / horizontal mixer and carbonized for 24 hours at a temperature of 1,500°C, thereby granulating scaly primary particles and producing artificial graphite having spherical secondary particle morphology. However, before and / or after carbonization, a magnetic field of 30,000 G to 32,000 G was applied to the graphitized product using an electromagnet for 10 to 300 seconds to adjust the concentration of transition metal particles present in the product. The concentration adjustment points are shown in Table 1 below.

[0108] The artificial graphite samples were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Specifically, 100 g of each artificial graphite sample was added to 200 mL of ethanol. A Teflon magnet (magnetic field strength: approximately 5000 ± 100 G) was placed in the ethanol containing the artificial graphite and mixed for 2 hours. After mixing, the magnet was removed from the ethanol and placed in a Teflon vial. 15 mL of aqua regia was added and heated at 150 °C for 3 hours. The heated aqua regia was cooled to room temperature and then filled with ultrapure water to a total volume of 50 mL to prepare the sample. A calibration curve was created for standard solutions of 0.1 mg / kg, 0.5 mg / kg, and 1.0 mg / kg using an inductively coupled plasma optical emission spectroscopy (model: OPTIMA AVIO 500, manufacturer: PERKIN-ELMER), and the sample samples were analyzed. At this time, the detection limit (Method Detection Limit, MDL) was set to less than 50 μg / kg (<50 μg / kg).

[0109] As a result, it was confirmed that the artificial graphite contained particles containing iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr), zinc (Zn), magnesium (Mg), manganese (Mn), and copper (Cu) uniformly dispersed within. The (1) total concentration of transition metals, (2) the individual concentrations of iron (Fe) and nickel (Ni), and (3) the concentration ratio of iron to nickel contained within the artificial graphite are shown in Table 1 below.

[0110] [Table 1]

[0111] 2) Manufacturing of negative electrodes Carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) were prepared as binders. Then, 96 parts by weight of the artificial graphite of Preparation Examples 1 to 10 prepared above, 1.5 parts by weight of carboxymethyl cellulose (CMC), and 2.5 parts by weight of styrene-butadiene rubber (SBR) were mixed with water to a solid content of 50% to prepare a negative electrode slurry.

[0112] The prepared negative electrode slurry was applied onto a copper sheet (thickness: 10 μm) that was being transferred roll-to-roll (transfer speed: 5 m / min) using a die coater.

[0113] The coated negative electrode slurry was dried with hot air to form a negative electrode active layer on the negative electrode current collector. The formed negative electrode active layer was rolled at 50±1°C under a pressure of 100 MPa to 150 MPa and a transfer speed of 3 m / s to prepare a negative electrode for a lithium secondary battery (average thickness of negative electrode active layer: 160±5 μm). The type of artificial graphite used in each negative electrode is shown in Table 2 below.

[0114] [Table 2]

[0115] <Examples 9 to 16 and Comparative Examples 6 to 10. Production of Lithium Secondary Batteries> LiNi with a particle size of 5 μm is used as the positive electrode active material. 0.7 Co 0.1 Mn 0.1 Al 0.1 O2 was prepared and mixed with polyvinylidene fluoride as a carbon-based conductive material and binder in N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3 to form a slurry, which was then cast onto an aluminum sheet, dried in a vacuum oven at 120°C, and rolled to produce a positive electrode.

[0116] A separator made of 18 μm polypropylene was interposed between the obtained positive electrode and the negative electrode produced in each of Examples 1 to 8 and Comparative Examples 1 to 5, and the resulting electrode was inserted into a case, and then an electrolyte composition was injected to assemble a mono-cell for a lithium secondary battery.

[0117] The type of negative electrode used in each lithium secondary battery is shown in Table 3 below.

[0118] [Table 3]

[0119] <Experimental Example> In order to evaluate the performance of the negative electrode according to the present invention, the following experiments were carried out on the negative electrodes and lithium secondary batteries prepared in the examples and comparative examples.

[0120] 1) High-speed DC resistance evaluation of secondary batteries The mono-cells manufactured in Examples 9 to 16 and Comparative Examples 6 to 10 were activated by charging them at 25°C in a constant current-constant voltage (CC-CV) mode at 0.1 C up to 4.25 V, and then discharging them at a constant current of 0.1 C down to 3.0 V.

[0121] The DC resistance (DC-IR) of each activated mono cell was measured while charging it to 50% SOC at a constant current of 2.5 C for 30 seconds at 25° C. The measured results are shown in Table 4 below.

[0122] 2) High temperature life evaluation The mono-cells manufactured in Examples 9 to 16 and Comparative Examples 6 to 10 were activated by charging them at 25°C in a constant current-constant voltage (CC-CV) mode at 0.1 C up to 4.25 V, and then discharging them at a constant current of 0.1 C down to 3.0 V.

[0123] After that, each mono cell was charged at 45°C with a constant current (CC) of 1C and discharged at a constant current (CC) of 1C, and 300 cycles of charge and discharge were performed. st Charging capacity and 300 cycles th The charge capacity of the cycle was measured. st Based on charging capacity of 300 cycles th The charge capacity retention rate of each cycle was calculated, and the high-temperature life of each mono-cell was evaluated. The results are shown in Table 4 below.

[0124] [Table 4]

[0125] As shown in Table 4 above, it can be seen that the negative electrode for a lithium secondary battery according to the present invention has low DC resistance during high-rate charge / discharge and is excellent in high-temperature charge / discharge performance.

[0126] Specifically, the secondary batteries of the examples, in which the concentrations and concentration ratios of iron and nickel contained in the carbon-based negative electrode active material satisfied the specified ranges, exhibited a low DC resistance of less than 1810 mΩ during high-rate charging and discharging at 2.5 C, and a high capacity retention rate of approximately 83% or more during high-temperature charging and discharging.

[0127] On the other hand, the secondary battery of Comparative Example 6 had a significantly lower concentration of transition metal particles in the carbon-based negative electrode active material compared to the Examples, but the concentration ratio of iron and nickel was also significantly lower, and it was confirmed that the DC resistance during high-rate charge / discharge exceeded 1800 mΩ and the capacity retention rate during high-temperature charge / discharge was less than 83%.

[0128] This means that even if a carbon-based negative electrode active material contains a certain amount of transition metal particles, the DC resistance during high-rate charge / discharge of the negative electrode and the capacity retention rate during high-temperature charge / discharge can be improved as long as the concentrations of iron and nickel and the ratio of these concentrations satisfy predetermined ranges.

[0129] These results show that the negative electrode for a lithium secondary battery according to the present invention has the advantages of excellent life characteristics under high temperature conditions and low electrical resistance under high speed conditions.

[0130] Although the present invention has been described above with reference to preferred embodiments, it will be understood that a person skilled in the art or having ordinary knowledge in the art can make various modifications and changes to the present invention without departing from the technical scope of the present invention as set forth in the claims below.

[0131] Therefore, the technical scope of the present invention is not limited to the content described in the Summary of the Invention of the specification, but can be defined by the claims.

Claims

1. a negative electrode current collector; and a negative electrode active layer provided on at least one surface of the negative electrode current collector and including a carbon-based negative electrode active material; the carbon-based negative electrode active material contains magnetic transition metal particles at a concentration of 1,200 ppm or less; the transition metal particles include iron and nickel; A negative electrode in which the concentration ratio of iron to nickel (Fe / Ni) contained in the carbon-based negative electrode active material is in the range of 2.5 to 13.

0.

2. 2. The negative electrode according to claim 1, wherein the concentration of iron contained in the carbon-based negative electrode active material is in the range of 0.1 ppm to 1,000 ppm.

3. 3. The negative electrode according to claim 1, wherein the concentration of nickel contained in the carbon-based negative electrode active material is in the range of 0.01 ppm to 500 ppm.

4. 3. The negative electrode according to claim 1, wherein the carbon-based negative electrode active material contains the magnetic transition metal particles at a concentration in the range of 0.01 ppm to 1,100 ppm.

5. The negative electrode according to claim 1 or 2, wherein the magnetic transition metal particles contained in the carbon-based negative electrode active material contain iron in an amount of 50% or more by weight based on the total weight.

6. The negative electrode according to claim 1 or 2, wherein the magnetic transition metal particles contained in the carbon-based negative electrode active material further contain one or more of cobalt, chromium, zinc, magnesium, manganese, and copper.

7. The negative electrode according to claim 1 or 2, wherein the carbon-based negative electrode active material is artificial graphite in the form of secondary particles formed by granulating primary particles.

8. a step of applying a negative electrode slurry containing a carbon-based negative electrode active material to at least one surface of a negative electrode current collector and drying the slurry to form a negative electrode active layer; the carbon-based negative electrode active material contains magnetic transition metal particles, the transition metal particles include iron and nickel; the carbon-based negative electrode active material contains the transition metal particles at a concentration of 1,200 ppm or less; The concentration ratio of iron to nickel (Fe / Ni) contained in the carbon-based negative electrode active material is in the range of 2.5 to 13.

0.

9. The carbon-based negative electrode active material is A step (S1) of graphitizing a carbon raw material; and (S2) carbonizing the graphitized carbon raw material, 9. The method for producing a negative electrode according to claim 8, wherein the graphitized carbon raw material is produced by a method including a step (S3) of adjusting a concentration of magnetic transition metal particles present in the carbon raw material by applying a magnetic field at least once before and after the carbonization step.

10. 10. The method for manufacturing a negative electrode according to claim 9, wherein in the step (S3) of adjusting the concentration of the transition metal particles contained in the carbon-based negative electrode active material, the magnetic field is applied at an intensity in the range of 1,000 G to 40,000 G for 1 second to 600 seconds.

11. 10. The method of claim 9, wherein the step (S3) of adjusting the concentration of the transition metal particles contained in the carbon-based negative electrode active material is performed before or after the step of carbonizing the graphitized carbon raw material.

12. 10. The method for producing a negative electrode according to claim 8, wherein the concentration of iron contained in the carbon-based negative electrode active material is in the range of 0.1 ppm to 1,000 ppm.

13. 10. The method for producing a negative electrode according to claim 8, wherein the concentration of nickel contained in the carbon-based negative electrode active material is in the range of 0.01 ppm to 500 ppm.

14. The method for manufacturing a negative electrode according to claim 8 or 9, wherein the transition metal particles contained in the carbon-based negative electrode active material further contain at least one of cobalt, chromium, zinc, magnesium, manganese, and copper.

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